The following messages can be resent:

• Sent messages that have been assigned output sequence numbers
• Sent messages that remain in the output queue
• Messages sent to terminals

If the message to be resent is not found in the message queue (disk queue), the function dc_mcf_resend() returns with an error.

Messages to be resent are identified using the following information which was specified on the sent message:

• Output destination logical terminal name
  The output destination logical terminal name determines the output queue which contains the message to be selected.
  
• Message output sequence number
  Output sequence numbers can be set in one of the following ways. When resending messages, it is possible to give them new output sequence numbers:
  
  1. Output sequence number of the message to be resent
  2. Specification that, of all the sent messages, the message with the last output sequence number is to be resent.
• Message type (general branch or priority branch)
  When a message is resent, its message type can be newly specified.
  

Resending of a message requires the use of a work area with the size equal to the maximum segment length specified for the -e option to the UAP common definition (mcfmuap) included in the MCF manager definition. If the segment of the message being resent is larger than this work area, the function dc_mcf_resend() returns with an error. Therefore, the value specified for the -e option to the UAP common definition must be at least the maximum length of the message to be resent.

More than one message with the same sequence number may be present in the message queue file, depending on the sequence number specification given in the -l option to the UAP common definition included in the MCF manager definition. In this case, which message is resent is unpredictable.